Determining the Best Fuzzy Gamma Coefficient and Landslide Hazard Zoning in Qezelozan Watershed

Landslide is one of the most destructive types of erosion on slopes, which causes a lot of financial and human losses. Identifying the effective factors in landslide occurrence and preparing a landslide hazard zonation map is one of the basic tools to manage and reduce potential damage. The purpose of this study is to evaluate the efficiency of fuzzy gamma operators and landslide hazard zonation in the Qezelozan watershed of Qazvin province. The landslide inventory map and also 11 effective factors including slope, slope direction, altitude, land use, lithology, distance to road, distance to stream, distance to fault, earthquake acceleration, precipitation, and maximum daily precipitation were first prepared. Then, the values of frequency ratio and fuzzy membership were calculated for each class of effective factors. In the next step, the landslide susceptibility maps were produced using fuzzy gamma operators. A total of 17 landslides were identified, 70% (11 landslides with an area of 153 hectares) of which were used to model and 30% (6 landslides with an area of 60 hectares) of which were used to evaluate the results of the models. The evaluation process using Density Ratio and Sum of Quality indices showed that the gamma of 0.96 has higher accuracy than other gamma values in the study area. The landslide hazard zoning map of the superior model will be useful in land use planning and reducing the landslide risk of the region.